In the related art, as one type of an escapement of a mechanical timepiece, a “detent escapement” (chronometer escapement) is known. As a representative mechanism form of the detent escapement, conventionally, a spring detent escapement and a pivoted detent escapement have been widely known (for example, refer to NTL 1 below).
Referring to FIG. 32, the conventional spring detent escapement 800 includes an escape wheel 810, a balance 820, a detent lever 840, and a balance spring 830 which is configured of a plate spring. An impulse pallet 812 is fixed to a roller table of the balance 820. A locking stone 832 is fixed to the detent lever 840.
Referring to FIG. 33, the conventional pivoted detent escapement 900 includes an escape wheel 910, a balance 920, a detent lever 930, and a balance spring 940 which is configured of helical spring (spiral spring). An impulse pallet 912 is fixed to a roller table of the balance 920. A locking stone 932 is fixed to the detent lever 930.
Unlike a club tooth lever escapement which is widely used currently, as characteristics common to the above-described two types of escapement, since power is directly transmitted from the escape wheel to the balance, there is an advantage in that a loss of the power (transmission torque) in the escapement can be decreased.
The conventional first type of detent escapement includes a detent lever, a helical spring (spiral spring), and a plate spring (for example, refer to PTL 1 below).
The conventional second type of detent escapement includes a major roller (4) which supports a first finger (14), a determent member (6) which supports a second finger (11) and a determent pawl stone (7), and a small roller (23) which performs the position control of the determent member (6). The detent escapement does not include a return spring (for example, refer to PTL 2 below).
The conventional third type of detent escapement includes an escape wheel (1), a balance, a detent (11) which supports a stop pawl (21), and a restricting plate (5) which is fixed to the balance. The detent escapement includes a balance spring (12) in which the inner end is integrated to the detent (11) (for example, refer to PTL 3 below).
The conventional method for manufacturing electroformed components such as a pallet fork and the escape wheel includes a process that forms an etching hole on a substrate having a mask, a process that inserts a lower shaft portion including a tip of the lower shaft portion of a shaft component into the etching hole of the substrate, and a process that performs an electroforming process with respect to the substrate to which a portion of the shaft component is inserted and forms an electroforming metal portion which is integrated to the shaft component (for example, refer to PTLs 4 to 7 below).